The closer we get to true artificial intelligence, the closer we also get to artificial stupidity.

It's a sad, sad story, and not an uncommon one.

My 2008 VW Jetta has the expensive VW-provided electrical interface for trailer lights. The computer sends pulses to the trailer and tells you if a globe is blown. It's clever enough to even sense whether it's the right or left hand globe if it's a stop or tail light. Neat.

Interesting fact number one: It doesn't work with LED lights. Plug in a trailer with incandescent globes and it's a marvel. Plug in one with LED lights...

If you're lucky, the lights will all still work, just the indicators will both strobe dimly. If not, some or all of the lights will strobe dimly, and some or all of them won't otherwise give a glimmer. This is a common problem, not just with VW cars, with many others. I guess the designers didn't know about LED lights? Wrong.

Interesting fact number two: The Jetta is itself fitted with LED brake, tail and turn lights. It's not that the designers didn't know that LEDs existed (although that would be pathetic enough). They just didn't think, or didn't care, or both.

Interesting fact number three: Somebody was PAID to design this high-priced muckup (original word censored). And I guess they're still designing Volkswagens. You have been warned. I mean, perhaps they don't apply the same half-dead brains to designing the electronic throttle and transmission and airbag systems. Perhaps. But remember the Lexus that went off the road at high speed in the USA a few years back? Killing a family of four? The pathetic cell phone pleas from the father who was unable to slow the card down and was vainly struggling to keep it on the road?

All because some designer didn't think too well. Perhaps Volkswagen use the same designer. It would explain a lot, and be interesting to know. They definitely seem to use the same quality control on their designs... meaning too little if any. It would be interesting to know what if any design review program this muckup passed, and if it did pass, why. Meanwhile, you have been warned.

I love my Jetta. It has done everything I wanted with a minimum of fuss and a lot of driving pleasure. And this particular muckup is so easy to fix. I might even sell you one if you ask nicely. Stay tuned.

Or meantime a few hints...

https://www.autobarn.com.au/ledautolamps-12-volt-load-resistor-lr12-2 21W $25 for two (you may need four, or it may be enough just to load the turn indicator circuits and the brake and tail lights will then be OK too... depends on the vehicle)

http://www.ebay.com.au/bhp/led-load-resistor 25W or 50W, packs of two from $3.39, four from $6.37

To do it neatly, and to get a useful gadget that will allow you to tow any trailer with any car, you could just make up a male-to-female lead with the resistors in it. They go in parallel to the lights... if you don't know what this means and/or why it's important, then get someone who does to wire it up for you.

Wonder why the auto shops don't sell them ready made up?

And a warning

These things get hot. Read the instructions, carefully! They should tell you to mount them on metal, and to make sure the metal is itself well cooled. Do it. Maybe mount a removable weatherproof box on the trailer drawbar, with a metal side of the box against the metal of the bar, and the resistors mounted on that metal side.